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      <title>Nginx反向代理 - 交互式测验</title>
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          padding: 20px 30px;
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          min-height: 65px; /* Reserve space */
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        .nav-btn {
          background-color: #4a90e2;
          color: white;
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          border-radius: 8px;
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          cursor: pointer;
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Nginx反向代理 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档描述，Nginx反向代理与正向代理最核心的区别是什么？",
    "options": [
      "反向代理主要用于缓存静态文件，而正向代理用于动态内容。",
      "反向代理对客户端是透明的，隐藏了后端服务器；正向代理对服务器是透明的，隐藏了客户端。",
      "反向代理需要客户端进行特殊配置才能使用，而正向代理不需要。",
      "反向代理只能处理HTTP请求，而正向代理可以处理所有类型的网络协议。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，在反向代理中，客户端无需知道后端服务器的存在，代理隐藏了内部服务器。而在正向代理中，是客户端配置代理去访问外部资源，代理隐藏了客户端的真实身份。因此，核心区别在于代理服务所隐藏和服务的对象不同。",
    "source": "文档中「1. 反向代理的基本概念」部分",
    "hint": "思考一下，当您访问一个大型网站时，您知道是哪台具体的服务器在为您服务吗？这个场景体现了哪种代理的特点？"
  },
  {
    "question": "当Nginx作为负载均衡器时，如果希望来自同一个用户的请求始终被分发到同一台后端服务器处理（例如为了维持会话状态），应该选择哪种负载均衡策略？",
    "options": [
      "轮询 (Round-robin)",
      "最少连接 (Least Connections)",
      "IP哈希 (IP Hash)",
      "加权轮询 (Weighted Round-robin)"
    ],
    "correctAnswerIndex": 2,
    "explanation": "IP哈希（IP Hash）策略通过计算客户端IP地址的哈希值来决定将请求分发到哪台后端服务器。只要客户端的IP地址不变，其请求就会一直由同一台服务器处理，这对于需要保持会话一致性的应用场景非常有用。",
    "source": "文档中「3.1 负载均衡」部分",
    "hint": "文档中提到了一种“根据客户端IP地址进行哈希分配”的策略，它的主要目的是什么？"
  },
  {
    "question": "在Nginx反向代理的配置中，哪个指令是实现请求转发至后端的关键核心指令？",
    "options": [
      "listen",
      "upstream",
      "proxy_pass",
      "proxy_set_header"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`proxy_pass`是Nginx反向代理配置的核心指令，它用于指定将客户端的请求转发到哪个后端服务器地址或`upstream`定义的服务器池。",
    "source": "文档中「4. Nginx反向代理的配置」部分",
    "hint": "在配置示例中，有一个指令直接指向了后端服务器地址 `http://backend_server`，这个指令是什么？"
  },
  {
    "question": "将SSL/TLS的加密解密过程放在Nginx层处理，而不是在后端应用服务器上，这种做法被称为“TLS/SSL终端代理”。其主要优势是什么？",
    "options": [
      "增强了后端服务器之间的通信加密。",
      "为后端服务器自动续签SSL证书。",
      "减轻后端服务器的CPU计算负担，提升性能。",
      "强制所有客户端必须使用最新版本的TLS协议。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "SSL/TLS的加密和解密是计算密集型操作，会消耗大量的CPU资源。将这些工作集中到Nginx代理服务器上完成，可以让后端应用服务器专注于处理业务逻辑，从而减轻其负担并提升整体系统性能。",
    "source": "文档中「3.3 TLS/SSL终端代理」部分",
    "hint": "文档提到这种做法可以“减轻后端服务器的负担，提升性能”，这是通过转移哪种类型的计算任务实现的？"
  },
  {
    "question": "以下哪项不属于文档中提到的Nginx作为反向代理的常见用途？",
    "options": [
      "作为数据库的中间件，直接处理SQL查询。",
      "通过缓存静态内容来加速网站访问。",
      "将客户端请求分发到多个后端服务器以实现负载均衡。",
      "作为安全防火墙，保护后端服务器免受网络攻击。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档列举了Nginx反向代理的多种用途，包括负载均衡、缓存加速、安全隔离（防火墙）、TLS/SSL终端代理和WebSocket代理。但是，Nginx是一个Web服务器和反向代理服务器，通常工作在应用层（HTTP/HTTPS），它不直接作为数据库中间件来处理SQL查询。",
    "source": "文档中「3. Nginx反向代理的常见用途」部分",
    "hint": "请回顾文档中列出的几个主要应用场景，思考哪一个选项描述的功能超出了Web代理的范畴。"
  },
  {
    "question": "为了提升Nginx反向代理的性能，`keepalive`指令起到了什么作用？",
    "options": [
      "启用Gzip压缩，减小传输数据体积。",
      "定期检查后端服务器是否存活。",
      "维持Nginx与后端服务器之间的持久连接，减少连接建立的开销。",
      "设置静态资源的缓存过期时间。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`keepalive`指令用于配置Nginx与后端服务器之间的连接池。通过维持一定数量的持久连接（长连接），可以避免为每个新的客户端请求都与后端服务器重新建立TCP连接，从而显著减少了网络握手带来的延迟和系统开销。",
    "source": "文档中「5.2 连接池配置」部分",
    "hint": "该优化措施旨在“减少与后端服务器的连接开销”。想一想，网络通信中哪一步的开销是比较大的？"
  },
  {
    "question": "在Nginx配置中，`upstream`块的主要功能是什么？",
    "options": [
      "定义Nginx监听的端口和域名。",
      "设置需要转发给后端的HTTP头部信息。",
      "根据URL路径匹配不同的处理规则。",
      "定义一个后端服务器组（服务器池），用于负载均衡。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "`upstream`指令块用于定义一组后端服务器，并为这个组命名。之后，`proxy_pass`指令可以直接引用这个组名，Nginx会根据配置的负载均衡策略将请求分发到组内的某台服务器上。",
    "source": "文档中「4. Nginx反向代理的配置」部分",
    "hint": "在负载均衡的配置示例中，多个后端服务器是如何被组织在一起的？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
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        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
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            li.textContent = optionText;
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            // 如果这道题已经回答过，恢复状态
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            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
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            nextBtn.style.display = 'block';
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            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
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        function showResult(isCorrect, questionData) {
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            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
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            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
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        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

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            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  